Building a supermassive black hole in under a billion years

We know they're out there, but we don't know how they got there.

The merger of early galaxies could bring two supermassive black holes together. But how did they get so big in the first place?

Jillian Bellovary, Fabio Governato

Decades of astronomy have revealed that supermassive black holes, weighing up to billions of times the mass of the Sun, inhabit the centers of most galaxies, if not all of them. In some galaxies, these black holes power quasars, in which the energetic matter near the black hole emits copious amounts of light. This output has helped us spot quasars at great distances, meaning they date from when the Universe was just a few hundred million years old.

That raises an obvious question: how can you build something that big in such a (relatively) short matter of time? A review in today's issue of Science (part of a series of articles dedicated to black holes) describes several potential means for generating a black hole of this size on a very tight schedule.

Most black holes are produced by supernovae, triggered by stars that are less than 100 times the mass of the Sun. These leave behind black holes that are just a few times the solar mass. While these can grow by drawing in material from their environment, it would require a very high rate of growth for a very long time—it's simply not realistic for these to have given rise to the giants at galaxies' cores.

But there are lots of reasons to think they wouldn't need to. Several models of star formation indicate that the first stars were hundreds of times the mass of the Sun, much larger than any stars we're certain exist today. That's because they formed in the absence of heavier elements, which allow for a more efficient star formation by radiating away heat generated by the gravitational collapse of the star. With none of these heavy elements around, stars had to be much heavier to overcome their own heat.

At the high end, these ultra-heavyweights did not have the sort of life cycle we associate with stars in the current Universe. Modern stars find a balance between the inward force of gravity and the outward pressure driven by fusion, and can burn for billions of years. In these early stars, gravity is so large that fusion never has a chance—they simply collapse directly into a black hole that weighs in at around 200 times the mass of the Sun. If enough of these formed in the heart of early galaxies, mergers and a rapid accumulation of gas might be sufficient to grow them rapidly.

A variation on this idea shifts the mergers earlier. In this model, the initial stars don't have to be as large—which may be a good thing, given that some models of star formation are now suggesting lighter stars could have formed in the early Universe. In the dense centers of the earliest galaxies, however, these stars could collide and merge, forming a supermassive star, a few thousand times the mass of the Sun. If this happens rapidly enough, the star could collapse directly into a black hole that is 1,000 times the mass of the Sun.

Finally, the most exotic option being considered is one where dynamic instabilities in a large gas cloud could create a sudden and rapid infall that's fast enough to overcome the outward pressure of fusion. In this case, the core of the star would collapse into a black hole even as more material keeps falling into the body's outer layers. This would create something that's a hollow shell of "star" surrounding a large black hole that would siphon off material just a bit faster than it arrived. By the time the black hole had swallowed the shell entirely, models suggest it could be as massive as a million Suns.

How can we distinguish among these models? One option would be to study more quasars at the most distant edges of the visible Universe, since these would be the oldest and thus the closest to the original formation of their black holes. But the best option would be to have a record of the violent events that produce them. For that, we have to wait for the further development of gravity wave detectors.

Mergers of early galaxies would combine their central black holes, building them up to even greater masses. (Video via AAAS/Jillian Bellovary, Fabio Governato)

None of these mechanisms provide for a black hole with billions of solar masses. But the star forming regions of the early Universe were probably dense enough that collisions among small protogalaxies were common, and these should lead to mergers of these central black holes. But that's something we do have a grip on, as demonstrated by a video of merger simulations that accompanied Science's black hole package.

If I had one dying wish it would be to have a time machine. That way I could go back to the early universe and watch all this happen. Of course I'd have to have a remote as well, so I can fast forward through millions of years easily. And it of course have to be pressurized time machine with AC, have a giant window for viewing, maybe a big bay window, and lazy boy recliner. That way one could take in the view with style. Oh, and Jim Morrison and Elvis would have to be there as well. We'd all smoke out and watch the universe evolve and get all philosophical and stuff. Oh, almost forgot..... Carl Segan would be there too. Not just for good karma and all, but because he had a penchant for the bud as well and one couldn't in good conscious not invite him. Kick back with some kind, watch the universe evolve hanging out with Jim and Elvis while listening to the dulcet tones of Carl explain it all....

Absolutely amazing video, makes me wonder why I haven't seen more like those before. The scale of the whole thing is hard to fathom though, but i tried imagining earth as a small part of one of those particles.

If I had one dying wish it would be to have a time machine. That way I could go back to the early universe and watch all this happen. Of course I'd have to have a remote as well, so I can fast forward through millions of years easily. And it of course have to be pressurized time machine with AC, have a giant window for viewing, maybe a big bay window, and lazy boy recliner. That way one could take in the view with style. Oh, and Jim Morrison and Elvis would have to be there as well. We'd all smoke out and watch the universe evolve and get all philosophical and stuff. Oh, almost forgot..... Carl Segan would be there too. Not just for good karma and all, but because he had a penchant for the bud as well and one couldn't in good conscious not invite him. Kick back with some kind, watch the universe evolve hanging out with Jim and Elvis while listening to the dulcet tones of Carl explain it all....

From what I mean is ... if you look at raw (aka, actual photos/videos) in space, it is mostly different shades of grey. I need to find the article on that subject though. That is why I am curious on why random colors were added to that video.

Yeah. I makes me think that the density of gas of the early universe slowed down the movements enough so far more collisions happens than expected. This would, of course, increase the size of early black holes.

From what I mean is ... if you look at raw (aka, actual photos/videos) in space, it is mostly different shades of grey. I need to find the article on that subject though. That is why I am curious on why random colors were added to that video.

I'd imagine the color is derived from the mass and temperature of each particle in the simulation; when particles collide, they get bigger and hotter. Or maybe it's meant to represent wavelengths (black holes are bright in the X-ray region IIRC).

"The explanation that’s left is that of an eclipsing contact binary system (“contact” means that the stars are so close to each other that their atmospheres form one common envelope. A free, interactive demo can be found here.) This explains the periodic behavior of the light curve: the stars pass in front of each other, blocking out some of the light each time around. It also explains the decreasing period: the two stars are getting closer together and so, by Kepler’s 3rd law, their orbital period shrinks.

And the 2008 eruption, how does that fit into the binary system scenario? That’s the two stars merging together. The merging of the two stars released a lot of energy, producing the bright outburst that first brought attention to V1309 Sco. A single star was left behind after the outburst, which has been gradually cooling since. The full light curve, from 2001 to 2010, is shown in the figure below. Although predicted by theory and generally expected, this is the first direct evidence that contact binaries merge to form a single star."

The simulation is missing two features which are common to black holes and galaxies:

1. The relativistic jets perpendicular to the accretion disk of accelerated matter the BH spins out as the magnetic fields twist and spit out energy and matter around poles of rotation. http://en.wikipedia.org/wiki/Relativistic_jet

That is an effect of dark matter embedding the optically visible galaxy, nothing nonsensical or unexpected about it.

The method of simulation or what we are shown isn't stated. If they didn't include dark matter it would only be proof of principle on SMBH merging when translated to the actual physics.

If they included dark matter and shows it, which is what I assumed, the rotation curve would drop off at the dark matter edges of a galaxy. (Analogous to an all baryonic structure.)

Mostly I suspect it is a model agnostic on the type of particles, as it works either way you interpret it. The natural way would then be to interpret it as dark matter, as it dominates the matter content of structures.

If I had one dying wish it would be to have a time machine. That way I could go back to the early universe and watch all this happen. Of course I'd have to have a remote as well, so I can fast forward through millions of years easily. And it of course have to be pressurized time machine with AC, have a giant window for viewing, maybe a big bay window, and lazy boy recliner. That way one could take in the view with style. Oh, and Jim Morrison and Elvis would have to be there as well. We'd all smoke out and watch the universe evolve and get all philosophical and stuff. Oh, almost forgot..... Carl Segan would be there too. Not just for good karma and all, but because he had a penchant for the bud as well and one couldn't in good conscious not invite him. Kick back with some kind, watch the universe evolve hanging out with Jim and Elvis while listening to the dulcet tones of Carl explain it all....

You realize that what we see as "supermasive black holes" (quasars/AGN's) don't necessarily have to be single black holes, right? They each could be several smaller black holes in relatively near orbit to one another.

You realize that what we see as "supermasive black holes" (quasars/AGN's) don't necessarily have to be single black holes, right? They each could be several smaller black holes in relatively near orbit to one another.

You realize what we see is history not the state these objects are in now.

THAT would be an interesting visualization: What does the universe look like now if there were no delay of c and we could see the state of these objects are in now.

The only reason they are struggling to justify these findings is because they base their timeline on the big bang. If you consider the placid universe theory, it becomes much simpler.

Are you referring to the steady-state model?

Problems with that include well-documented phenomena such as large variations in redshift among distant objects and the existence of the cosmic microwave background radiation. There also isn't very much evidence supporting it.

Nothing is being "based" on the concept of a big bang. It's simply the explanation that currently best fits the collected data. It probably isn't entirely correct, but a lot of other potential explanations have been eliminated through observation while it has not.

You realize what we see is history not the state these objects are in now.

THAT would be an interesting visualization: What does the universe look like now if there were no delay of c and we could see the state of these objects are in now.

That is the end result of the simulations, since the masses moves classically. You need to take relativity into account when comparing with observations.

wolfdagaz wrote:

The only reason they are struggling to justify these findings is because they base their timeline on the big bang. If you consider the placid universe theory, it becomes much simpler.

Wrong analysis. They aren't struggling, it is successful theory. This video was showing what we "have a grip on". The embarrassment of riches in suitable merger theories shows it is a fruitful area, but that testing lags behind.

Is that a steady state theory? They can no longer be fitted with observations (see for example Hoyle's problems for his theory at the end), so we know they aren't just inferior but they are factually wrong.

Yes, it is a steady state type of theory in which the universe, for all intent and purpose, has always been around and always will in one form or another, not rapidly expanding as the result of a giant detonation and became everything from nothing. We currently base the age of the universe on the big bang and how far we can see. Not so very long ago, we thought the world to be flat, then we were the center of the universe, now we are looking at it being 13.5 billion years old. As technology advances, so does the size of the universe. Interesting that the image we base this figure on is roughly the same in almost any direction (light allowing). This either once more makes us the center of the universe (interesting coinsidence) or there is more to see out there. Hubble himself stated that there were other possible reasons for the red shift (expanding universe), not the least of which is that light is subject to gravity and being filtered through dust and debris along that 13.5 billion light years of travel. I am confident that we will see technology add to that figure in time. We currently fill a huge amount of the universe with dark matter and dark energy to fudge the gap of what we don't know about the universe so that our theories make sense, because we hate to admit that we just don't know. The list of what we know is small, the unknown is huge, we fill the gap with guesses. We must take care not to string too many speculations together in a daisy-chain that leaps to a conclusion we can't test or observe and call it truth. We have seen such truth swing very wildly in our past, so I simply urge that people question and consider that there may always be more than we are seeing. You can't factor every variable and you don't always have all the data...even when you think you do. We are still children in our father's workshop. At the same time, I am giddy with what we may yet discover in the next few decades...provided we keep our eyes and minds open. The big bang MAY be the answer, but it is only one of the possible answers. Even the speed of light is still open to some debate and it is what we base even our fundamental calculations on. I know I tend to ruffle some feathers, but hope I have clarified my position.

You realize that what we see as "supermasive black holes" (quasars/AGN's) don't necessarily have to be single black holes, right? They each could be several smaller black holes in relatively near orbit to one another.

You realize what we see is history not the state these objects are in now.

THAT would be an interesting visualization: What does the universe look like now if there were no delay of c and we could see the state of these objects are in now.

Don't be ridiculous. The objects as we seen them (which is how they were in the past) don't necessarily have to be one single large object, but can be multiple objects in close proximity. It happens all the time in astronomy: mislabeling a cluster of stars as a single star, until someone takes a closer look at a different angle.

wolfdagaz wrote:

Yes, it is a steady state type of theory in which the universe, for all intent and purpose, has always been around and always will in one form or another, not rapidly expanding as the result of a giant detonation and became everything from nothing.

If the universe has always existed, there would already have been maximum entropy and heat death of the universe would have occurred. Needless to say, all stars would have burnt out by now, all stellar remnant cores would have radiated away all residual energy and would be non-rotating black dwarfs, there would be nearly no nebulae or hydrogen/helium clouds as the inevitable effects of gravity would have caused all free gasses to either collapse, or momentum would have caused them to spread out beyond the visible horizon. There would be no cosmic microwave radiation.

wolfdagaz wrote:

light is subject to gravity and being filtered through dust and debris along that 13.5 billion light years of travel. I am confident that we will see technology add to that figure in time.

What you say here is not impossible. However, I wonder why you feel so strongly that the current estimated age of the universe is incorrect. You have no actual observations that cast doubt on the consensus, correct?

The ironic part is that your last sentence is exactly my point. We have very little information on the formation or life cycles of stars, only a series of observations of billions of different events that we try to assemble into a single theory. Yes we observe entropy, we also speculate on the process of how stars are created and then die. Are there no new stars? What would the universe look like if matter continued to recycle? On the one hand, the gases and matter should all scatter and die out, yet on the other hand, we say that gravity would continue to bring such matter back together to recombine. Think of the big bang on a smaller scale for stars or even a galaxy. OR, even if the big bang is correct, we are speculating on the timeline. Over the years, we keep changing to math to fit the findings, then insist that because the math works, it proves the theory. Look at Einstien himself and his use of the cosmological constant. Hawking was adamant for years about information not escaping a black hole and then turned 180 on that later, causing all his followers to have to rethink their stand as well. I am only passionate about people remembering that these are only theories and to keep an open and questioning mind.